1. Field of the Invention
The present invention relates to analogs of biologically active, naturally occurring polyamines having a wide variety of therapeutic properties, as well as pharmaceutical compositions containing the analogs and their use in methods of therapeutic treatment.
2. Discussion of the Prior Art
In recent years, a great deal of attention has been focussed on the polyamines, e.g., spermidine, norspermidine, homospermidine, 1,4-diaminobutane (putrescine) and spermine. These studies have been largely directed at the biological properties of the polyamines probably because of the role they play in proliferative processes. It was shown early on that the polyamine levels in dividing cells, e.g., cancer cells, are much higher than in resting cells. See Janne et al, A. Biochim. Biophys. Acta., Vol. 473, page 241 (1978); Fillingame et al, Proc. Natl. Acad. Sci. U.S.A., Vol. 72, page 4042 (1975); Metcalf et al, J. Am. Chem. Soc., Vol. 100, page 2551 (1978); Flink et al, Nature (London), Vol. 253, page 62 (1975); and Pegg et al, Polyamine Metabolism and Function, Am. J. Cell. Physiol., Vol. 243, pages 212-221 (1982).
Several lines of evidence indicate that polyamines, particularly spermidine, are required for cell proliferation: (i) they are found in greater amounts in growing than in non-growing tissues; (ii) prokaryotic and eukaryotic mutants deficient in polyamine biosynthesis are auxotrophic for polyamines; and (iii) inhibitors specific for polyamine biosynthesis also inhibit cell growth. Despite this evidence, the precise biological role of polyamines in cell proliferation is uncertain. It has been suggested that polyamines, by virtue of their charged nature under physiological conditions and their conformational flexibility, might serve to stabilize macromolecules such as nucleic acids by anion neutralization. See Dkystra et al, Science, Vol. 149, page 48 (1965); Russell et al, Polyamines as Biochemical Markers of Normal and Malignant Growth (Raven, New York, 1978); Hirschfield et al, J. Bacteriol., Vol. 101, page 725 (1970); Hafner et al, J. Biol. Chem., Vol. 254, page 12419 (1979); Cohn et al, J. Bacteriol., Vol. 134, page 208 (1978); Pohjatipelto et al, Nature (London), Vol. 293, page 475 (1981); Mamont et al, Biochem. Biophys. Res. Commun., Vol. 81, page 58 (1978); Bloomfield et al, Polyamines in Biology and Medicine (D. R. Morris and L. J. Morton, eds., Dekker, New York, 1981), pages 183-205; Gosule et al, Nature, Vol. 259, page 333 (1976); Gabbay et al, Ann. N.Y. Acad. Sci., Vol. 171, page 810 (1970); Suwalsky et al, J. Mol. Biol., Vol. 42, page 363 (1969); and Liquori et al, J. Mol. Biol., Vol. 24, page 113 (1968).
However, regardless of the reason for increased polyamine levels, the phenomenon can be and has been exploited in chemotherapy. See Sjoerdsma et al, Butterworths Int. Med. Rev.: Clin. Pharmacol. Thera., Vol. 35, page 287 (1984); Israel et al, J. Med. Chem., Vol. 16, page 1 (1973); Morris et al, Polyamines in Biology and Medicine, Dekker, New York, page 223 (1981); and Wang et al, Biochem. Biophys. Res. Commun., Vol. 94, page 85 (1980).
Because of the role the natural polyamines play in proliferation, a great deal of effort has been invested in the development of polyamine analogs as anti-proliferatives [Cancer Res., Vol. 49, xe2x80x9cThe role of methylene backbone in the anti-proliferative activity of polyamine analogues on L1210 cells,xe2x80x9d Bergeron et al, pages 2959-2964 (1989); J. Med. Chem., Vol. 31, xe2x80x9cSynthetic polyamine analogues as antineoplastics,xe2x80x9d Bergeron et al, pages 1183-1190 (1988); Polyamines in Biochemical and Clinical Research, xe2x80x9cRegulation of polyamine biosynthetic activity by spermidine and sperminexe2x80x94a novel antiproliferative strategy,xe2x80x9d Porter et al, pages 677-690 (1988); Cancer Res., Vol. 49, xe2x80x9cMajor increases in spermidine/spermine-N1-acetyl transferase activity by spermine analogues and their relationship to polyamine depletion and growth inhibition in L1210 cells,xe2x80x9d Basu et al, pages 6226-6231 (1989); Biochem. J., Vol. 267, xe2x80x9cInduction of spermidine/spermine N1-acetyltransferase activity in Chinese-hamster ovary cells by N1,N11-bis(ethyl)norspermine and related compounds,xe2x80x9d Pegg et al, pages 331-338 (1990); Biochem. J., Vol. 268, xe2x80x9cCombined regulation of ornithine and S-adenosylmethionine decarboxylases by spermine and the spermine analogue N1N12-bis(ethyl)spermine,xe2x80x9d Porter et al, pages 207-212 (1990); Cancer Res., Vol. 50, xe2x80x9cEffect of N1,N14-bis(ethyl)-homospermine on the growth of U-87 MG and SF-126 on human brain tumor cells,xe2x80x9d Basu et al, pages 3137-3140 (1990); and Biochem. Biophys. Res. Commun., Vol. 152, xe2x80x9cThe effect of structural changes in a polyamine backbone on its DNA binding properties,xe2x80x9d Stewart, pages 1441-1446 (1988)]. These efforts have included the design of new synthetic methods [J. Org. Chem., Vol. 45, xe2x80x9cSynthesis of N4-acylated N1,N8-bis(acyl)spermidines: An approach to the synthesis of siderophores,xe2x80x9d Bergeron et al, pages 1589-1592 (1980); Synthesis, xe2x80x9cReagents for the selective acylation of spermidine, homospermidine and bis-[3-aminopropyl]amine,xe2x80x9d Bergeron et al, pages 732-733 (1981); Synthesis, xe2x80x9cReagents for the selective secondary functionalization of linear triamines,xe2x80x9d Bergeron et al, pages 689-692 (1982); Synthesis, xe2x80x9cAmines and polyamines from nitriles,xe2x80x9d Bergeron et al, pages 782-785 (1984); J. Org. Chem., Vol. 49, xe2x80x9cReagents for the stepwise functionalization of spermidine, homospermidine and bis-[3-aminopropyl]amine,xe2x80x9d Bergeron et al, page 2997 (1984); Accts. Chem. Res., Vol. 19, xe2x80x9cMethods for the selective modification of spermidine and its homologues,xe2x80x9d Bergeron, pages 105-113 (1986); Bioorg. Chem., Vol. 14, xe2x80x9cHexahydropyrimidines as masked spermidine vectors in drug delivery,xe2x80x9d Bergeron et al, pages 345-355 (1986); J. Org. Chem., Vol. 53, xe2x80x9cReagents for the stepwise functionalization of spermine,xe2x80x9d Bergeron et al, pages 3108-3111 (1988); J. Org. Chem., Vol. 52, xe2x80x9cTotal synthesis of (xc2x1)-15-Deoxyspergualin,xe2x80x9d Bergeron et al, pages 1700-1703 (1987); J. Org. Chem., Vol. 56, xe2x80x9cThe total synthesis of Alcaligin,xe2x80x9d Bergeron et al, pages 586-593 (1991); and CRC Handbook on Microbial Iron Chelates, xe2x80x9cSynthesis of catecholamide and hydroxamate siderophores,xe2x80x9d Bergeron et al, pages 271-307 (1991)] for the production of these analogs, as well as extensive biochemical studies focussed on the mechanism by which these compounds act [Cancer Res., Vol. 46, xe2x80x9cA comparison and characterization of growth inhibition by xcex1-Difluoromethylornithine (DFMO), and inhibitor of ornithine decarboxylase and N1,N8-bis(ethyl)spermidine (BES), an apparent regulator of the enzyme,xe2x80x9d Porter et al, pages 6279-6285 (1986); Cancer Res., Vol. 47, xe2x80x9cRelative abilities of bis(ethyl) derivatives of putrescine, spermidine and spermine to regulate polyamine biosynthesis and inhibit L1210 leukemia cell growth,xe2x80x9d Porter et al, pages 2821-2825 (1987); Cancer Res., Vol. 49, xe2x80x9cCorrelation between the effects of polyamine analogues on DNA conformation and cell growth,xe2x80x9d Basu et al, pages 5591-5597 (1989); Cancer Res., Vol. 49, xe2x80x9cDifferential response to treatment with the bis(ethyl)polyamine analogues between human small cell lung carcinoma and undifferentiated large cell lung carcinoma in culture,xe2x80x9d Casero et al, pages 639-643 (1988); Mol. Pharm., Vol. 39, xe2x80x9cSelective cellular depletion of mitochondrial DNA by the polyamine analog, N1,N12-bis(ethyl)spermine, and its relationship to polyamine structure and function,xe2x80x9d Vertino et al, pages 487-494 (1991); Biochem. and Biophys. Res. Comm., Vol. 157, xe2x80x9cModulation of polyamine biosynthesis and transport by oncogene transfection,xe2x80x9d Chang et al, pages 264-270 (1988); and Biopolymers, Vol. 26, xe2x80x9cStructural determinants of spermidine-DNA interactions,xe2x80x9d Vertino et al, pages 691-703 (1987)]. The mechanistic investigations have encompassed uptake studies, impact on polyamine analogs on polyamine pools and polyamine biosynthetic enzymes, as well as their effects on translational and transcriptional events.
Anti-neoplastic derivatives of the naturally occurring polyamines, pharmaceutical compositions and methods of treatment are also disclosed in the following pending patent application Ser. No. 08/231,692 filed Apr. 25, 1994, (xe2x80x9cSterically Hindered Tetraamines and Method for Their Productionxe2x80x9d), as well as in U.S. Pat. No. 5,091,576 issued Feb. 25, 1992; U.S. Pat. No. 5,128,353 issued, Jul. 7, 1992; and U.S. Pat. No. 5,173,505 issued Dec. 22, 1992. The disclosures of each of the foregoing applications and patents are incorporated herein by reference.
It is an object of the present invention to provide novel analogs of naturally occurring, biologically active polyamines which possess anti-neoplastic properties and to define the structural parameters which define compounds having such activities.
These and other objects are realized by the present invention, one embodiment of which relates to a polyamine having the formula: 
or a salt thereof with a pharmaceutically acceptable acid wherein:
R1-R6 may be the same or different and are alkyl, aryl, aryl alkyl, cycloalkyl, any of the foregoing wherein the alkyl chain is interrupted by at least one etheric oxygen atom, or hydrogen;
N1, N2, N3 and N4 are nitrogen atoms capable of protonation at physiological pH""s;
a and b may be the same or different and are integers from 1 to 4;
A, B and C may be the same or different and are bridging groups which effectively maintain the distance between the nitrogen atoms such that the polyamine:
(i) is capable of uptake by a target cell upon administration of the polyamine to a human or non-human animal; and
(ii) upon uptake by the target cell, competitively binds via an electrostatic interaction between the positively charged nitrogen atoms to substantially the same biological counter-anions as the intracellular natural polyamines in the target cell;
the polyamine, upon binding to the biological counter-anion in the cell, functions in a manner biologically different than the intracellular polyamines, the polyamine not occurring in nature.
Another embodiment of the invention comprises a pharmaceutical composition comprising an anti-neoplastic effective amount of the polyamine described above or a salt thereof with a pharmaceutically acceptable acid and a pharmaceutically acceptable carrier therefor.
An additional embodiment of the invention relates to a method of treating a human or non-human animal in need thereof comprising administering thereto an anti-neoplastic effective amount of the polyamine described above or a salt thereof with a pharmaceutically acceptable acid.